Warm and Wet or Hot and Dry Future Earth? The Dual Role of CO2 Explored with Fossil Plants

Leaf, Miocene, Australia.

Summary

CO2is a principal greenhouse gas that is increasing in the atmosphere at an unprecedented rate due to human activity, causing global climate change. It is predicted to continue to rise further and result in a perilous temperature increase of up to 4°C by the year 2100, but the relationship between concentrations of CO2 (pCO2) and temperature – the so-called climate sensitivity – is still not well understood.

Existing long-term pCO2 records and climate models still lack the resolution to precisely constrain the role of pCO2 in climate change, severely impeding our ability to project the consequences of future pCO2 rise.

This 4-year research project aims to reduce these uncertainties, by studying selected intervals of the Cenozoic era (the last 66 million years), which will serve as ‘climate change analogues’ for the future.

Firstly, new high-resolution pCO2 records will be constructed, using the stomatal proxy method with fossil plant leaves. Secondly, a novel approach included in this proposal is to explore the impact of pCO2 on plant transpiration: a major component of the Earth’s hydrological cycle, with direct implications for ecosystems. The identification of a new database of well-preserved and well-dated fossil leaves from the geological record of Australia and New Zealand offers this unique opportunity.

The results of the project will greatly improve our understanding of the dual role of pCO2 in climate change, and enable more accurate predictions for our future.

This research is funded by the Swedish Research Council (VR): Starter Grant